1. Field of the Invention
The present disclosure relates to microfracture stimulation and, more particularly, to a device for use in microfracture stimulation.
2. Related Art
Articulating body joints are surfaced with hyaline cartilage, which is a very durable low coefficient of friction natural material. These surfaces are often damaged when subjected to high repeated loading, such as when one runs. This is particularly true for lower body compressive joints such as the ankle, knee, hip and spine.
Resurfacing of the cartilage surfaces is a large area of study in the orthopaedic industry. One method is called microfracture. Rather than replacing the damaged articular cartilage with an artificial implant, microfracture stimulates the body to replace the surface with a fibrous cartilage. Fibrocartilage is not as robust and does not have the low coefficient of friction that hyaline cartilage does, but it does provide patients with reduced pain and enables then to participate in an active lifestyle.
Microfracture is created by first removing the damaged layer of cartilage. The damaged layer can vary from about 1 to about 6 mm in thickness. A sharp microfracture pick is then driven down about 2 to about 5 mm through the underlying subchondral bone to a blood supply. When the pick is removed, a small channel remains. Blood travels along the channels and clots in the area of the removed cartilage. The technique requires a series of such channels in the area of removed cartilage.
Microfracture pick have been created for use in this technique. The picks come with a sharp tip bent at various angles relative to the long axis of the pick's shaft. Typically, microfracture picks are available with tips having angles 20, 40, 60 or 90 degrees.
FIGS. 1 and 2 illustrate two prior art microfracture picks 10, 16. Each pick 10, 16 has a proximal end 12, 18 and a distal end 13, 20. Further, each pick 10, 16 has a sharp bent tip 14, 22 on its distal end 13, 20. The second pick 16 is identical to the first pick 10 except the second pick 16 has a tip 22 bent at a sharper angle.
FIG. 3 illustrates a handle 24 that is adapted for use with either the first pick 10 or the second pick 16. The handle 24 has an impact end 28 and a receiver end 26. The receiver end 26 includes a hole (not shown) to receive the proximal end 12, 18 of the picks 10, 16. In use, a surgeon assembles the pick 10, 16 to the handle 24, places the tip 14, 22 at the desired location for a channel, and hits the impact end 28 with a striking mass (not shown) until the tip 14, 22 is inserted approximately 2 to 5 mm through the underlying subchondral bone.
Since the handle 24 is designed to be struck on the impact end 28, the force is transmitted axially from the impact end 28 through a shaft of the pick 10, 16 and finally to the tip 14, 22. As the tip angle approaches 90 degrees, the axial impact does not transmit a force that acts in the direction of the tip. The result is that an elongated hole is made in the subchondral bone, which is not ideal, and it takes longer to get down to the blood supply. Additionally, when the tip is engaged in the subchondral bone and the proximal handle is struck with a striking mass, the tip is under large stress.
Therefore, there remains a need in the art for a microfracture pick that allows force to be transmitted in the direction of the tip even when the tip angle approaches 90 degrees.